title: Definitions of progression in chronic kidney disease--predictors and relationship to renal replacement therapy in a population cohort with a 6 year follow-up.
abstract: BACKGROUND
  Chronic kidney disease (CKD) is common, important and associated with increased healthcare needs due to CKD progression. Definitions of renal disease progression are multiple, and not always comparable. A measure of 'progression' directly comparable with renal replacement therapy (RRT) initiation would identify 'progressors' in research and for healthcare planning.
  
  
  METHODS
  The Grampian Laboratory Outcomes Morbidity and Mortality Study (GLOMMS-I) is a community cohort with CKD from 2003, followed up to June 2009 for (i) RRT initiation and (ii) 'progression': sustained reduction in estimated glomerular filtration rate (eGFR) by 15 mL/min/1.73 m2 (equivalent to CKD stage change), or to <10 mL/min/1.73 m2, whichever occurs first. Predictors were baseline demographics and comorbidity. The use of the Kidney Disease: Improving Global Outcomes-2012 progression definition was also explored.
  
  
  RESULTS
  Two thousand two hundred and eighty-nine and 1044 had Stage 3 and 4 CKD, 44% were males. Overall, RRT initiation and progression rates were 0.97 and 3.50 per 100 patient-years (py). Females had significantly lower progression and RRT initiation rates. The progression rate was not dependent on CKD stage [incidence rate ratio (IRR) for Stage 4 (versus Stage 3) 0.9 (95% CI 0.8-1.2)], whereas the RRT initiation rate was [IRR 5.6 (95% CI 3.8-8.2)]. Increased proteinuria was associated with both greater RRT initiation and progression rates.
  
  
  CONCLUSIONS
  Progression and RRT initiation rate ratios allow comparison of predictors of these outcomes. Higher rates of both in males suggest that greater RRT initiation rate is biological rather than due to preferential treatment. Similar progression but very different RRT initiation rates in Stage 3 and 4 CKD suggests that CKD stage effect on RRT initiation is a function of endpoint proximity rather than faster renal function deterioration.
authors.affiliation: Division of Applied Health Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: Angharad
authors.initials: A
authors.lastname: Marks
authors.forename: Nicholas
authors.initials: N
authors.lastname: Fluck
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Prescott
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Robertson
authors.forename: William G
authors.initials: WG
authors.lastname: Simpson
authors.forename: William Cairns S
authors.initials: WC
authors.lastname: Smith
authors.forename: Corri
authors.initials: C
authors.lastname: Black
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy; D017582:Renal Replacement Therapy; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
keywords: chronic kidney disease; cohort; progression; renal replacement therapy